This invention relates to plasticized polyvinyl chloride compositions and more particularly to polyvinyl chloride compositions containing an external plasticizer.
It is known that large amounts of plasticizers may be incorporated into polyvinyl chloride. This permits the processing of the resin to be made easier and also permits substantial improvement of the physical properties of the resin. The properties of polyvinyl chloride which may be improved by incorporating plasticizers depend upon the type of plasticizer. For example, when flexible vinyl plastics with flame-retardant properties are required, namely for floor coverings, electrical insulation and packaging, phosphate plasticizers and more particularly tricresyl phosphates are the most widely used.
Tricresylphosphate was one of the first plasticizers to be used with polyvinyl chloride. However, the poor low temperature properties of this phosphate, on one hand, and recurrent shortages of cresols, on the other hand, has led to efforts to substitute other plasticizers of the phsophate type for tricresyl phosphate. However, it appears that the improvement of one property of the vinyl resin generally takes place with accompanying detrimental changes of other properties when the heretofore known substitutes were tried. For instance, tri(ethylhexyl) phosphate imparts to polyvinyl chloride a better low temperature flexibility than tricresyl phosphate, but the plasticizer extraction by water or kerosene is drastically increased.
The object of the present invention is to provide plasticized polyvinyl chloride compositions wherein a new plasticizer of the phosphate type is employed.
Another object of the present invention is to provide a new and improved plasticized polyvinyl chloride wherein there is an improvement of the low temperature flexibility without detrimental effect or with little consequence on other valuable properties of the resin.
Still another object of the present invention is to provide a new and improved phosphate ester type plasticizer which may be substituted for tricresylphosphate as a plasticizer for polyvinyl chloride.